I've seen around Reddit that one reasons black Americans seem to excel at sports is because many of them come from an ancestry of slavery, and slaves were bred for certain attributes like strength, coordination, stamina, height, etc. Is there any historic evidence that slave owners consciously bred their slaves or forced certain slaves to breed? Did they have an advanced enough understanding of genetics, or was it trial and error? Is it all just total bullshit?
This question comes up every six months or so. Start in this thread, which may have some useful commentary for your questions. Naturally if someone has information to add to that, they'll hopefully chime in.
Since Evolution already breeds for strength, coordination, stamina, height, i doubt a bunch of people educated in science from the 1700's and 1800's could have done anything significant in only 5 - 10 generations, compared to 2 million years of Evolution.
And that's even if we assume Op's idea is correct, that owners were breeding for those attributes.